\documentclass{article}
\usepackage{amsmath}
\begin{document}

\section{Math Formulas}

\subsection{Inline Math}

The equation $E = mc^2$ is famous. Another inline formula: $\alpha + \beta = \gamma$.

\subsection{Display Math}

\[
  \int_0^\infty e^{-x^2} dx = \frac{\sqrt{\pi}}{2}
\]

\subsection{Equation Environment}

\begin{equation}
  f(x) = \sum_{n=0}^{\infty} \frac{x^n}{n!}
\end{equation}

\subsection{Align Environment}

\begin{align}
  a + b &= c \\
  d + e &= f
\end{align}

\end{document}
